It's theDrop-Drop Dropdown Menu...from WhowillbenexTech!

The Drop-Drop Dropdown Menu, the combination of a Suckerfish Dropdowns dropdown menu and a JavaScript animation script, drops down to a convenient location on your computer screen—for easier navigation—then drops off the screen when you’re through!

To use the Drop-Drop Dropdown Menu:
First, hover your cursor over the bony-fish suborder “Percoidei,”and then move your cursor down the web page, hovering over the fish family “Remoras.” Finally, carefully move your cursor to the right and click on the genus “Echeneis”...or just move the cursor down and click on one of the other genus names.